Caster assemblies are well-known and widely used in many industries. They are attached to carts, dollies, or other devices to provide easy movement of cumbersome or heavy objects. They may also be placed with other caster assemblies in an inverted orientation to form a rollerway facilitating the transport of heavy objects.
Caster assemblies may be characterized as rigid or swivel based on the type of movement they permit. Rigid caster assemblies permit only linear movement of the devices to which they are attached or the objects travelling over them. Swivel caster assemblies permit multi-directional movement of the devices to which they are attached or the objects travelling over them. Swivel caster assemblies may also be provided with a lock assembly which, when engaged, restricts the rotational movement of the assembly and thereby converts it to a rigid caster assembly.
To permit multi-directional movement, swivel caster assemblies typically include a wheel assembly attached to a top plate. The wheel assembly includes a swivel element attached to the lower face of the top plate, and legs projecting distally from the swivel element and attached by conventional means to a wheel. The swivel element enables the wheel to rotate about an axis perpendicular to the wheel's axis of rotation. In this way, the wheel can readily align itself in an appropriate direction under the influence of a load.
Conventional swivel caster assemblies typically utilize two sets of ball bearings to facilitate this swivel or rotational movement of the wheel assembly with respect to the top plate. A first ball bearing set is located between the swivel element and the top plate, and a second set ball bearing set is located between the swivel element and a cap which is rigidly attached to the top plate.
In conventional swivel caster assemblies, the first ball bearing set is uncovered and unprotected. The bearings of the first set are therefore exposed to dust, dirt, liquid, and other material found in industrial environments. As a result, the unprotected ball bearings become corrupted, and suffer impeded rolling action due to the presence of dirt or other particles. Impeded rolling action of the ball bearings results in impeded movement of the swivel element, which in turn results in impeded movement of the cart or device to which the caster assembly is attached. Indeed, ball bearing corruption in a swivel caster assembly may even cause the assembly to "freeze" or "lock up."
Further, because exposure to dust, dirt, and liquid corrupts the first ball bearing set of conventional swivel caster assemblies, the bearings require frequent lubrication-an inefficient and cumbersome process.
Finally, corruption of the first ball bearing set of conventional caster assemblies due to exposure to dust, dirt, and liquid decreases the service life of the entire swivel caster assembly. Once corrupted, the bearings themselves cannot efficiently be replaced. Instead, the entire swivel caster assembly must be replaced.
Accordingly, it is an object of the present invention to provide a seal for the first ball bearing set of a swivel caster assembly that increases the service life of the bearing set and the swivel caster assembly.
Another object of this invention is to provide a seal for the first ball bearing set of a swivel caster assembly that does not greatly increase the cost of the swivel caster assembly.
Yet another object of this invention is to provide a seal for the first ball bearing set of a swivel caster assembly that is secured to the swivel element of the assembly and accepts the pin of a swivel lock assembly, but does not wear rapidly from friction generated by rotation of the seal against the top plate.
A related object of this invention is to provide a swivel caster assembly in which the first ball bearing set is protected from exposure to and corruption by dust, dirt, and liquid, thereby increasing the service life of the both the ball bearing set and the entire swivel caster assembly.
Yet another related object of the invention is to provide a swivel caster assembly wherein the first ball bearing set is protected from corruption and therefore will not easily "lock up."
Other objects and advantages of the invention will become apparent to one skilled in the art upon reading the following detailed description and upon reference to the drawings. Throughout the drawings, like reference numerals refer to like parts.